<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>蜂窝纹路</title>

    <style>
    canvas { position: absolute; top: 0; left: 0; }

    /* Demo Buttons Style */
    .codrops-demos {
        font-size: 0.8em;
        text-align:center;
        position:absolute;
        z-index:99;
        width:96%;
    }

    .codrops-demos a {
        display: inline-block;
        margin: 0.35em 0.1em;
        padding: 0.5em 1.2em;
        outline: none;
        text-decoration: none;
        text-transform: uppercase;
        letter-spacing: 1px;
        font-weight: 700;
        border-radius: 2px;
        font-size: 110%;
        border: 2px solid transparent;
        color:#fff;
    }

    .codrops-demos a:hover,
    .codrops-demos a.current-demo {
        border-color: #383a3c;
    }
    </style>
</head>
<body>
    
    <canvas id="c"></canvas>

<script>
    var w = c.width = window.innerWidth,
h = c.height = window.innerHeight,
ctx = c.getContext('2d'),
opts = {
	len: 20,
	count: 50,
	baseTime: 10,
	addedTime: 10,
	dieChance: .05,
	spawnChance: 1,
	sparkChance: .1,
	sparkDist: 10,
	sparkSize: 2,
	color: 'hsl(hue,100%,light%)',
	baseLight: 50,
	addedLight: 10,
	shadowToTimePropMult: 6,
	baseLightInputMultiplier: .01,
	addedLightInputMultiplier: .02,
	cx: w / 2,
	cy: h / 2,
	repaintAlpha: .04,
	hueChange: .1
},
tick = 0,
lines = [],
dieX = w / 2 / opts.len,
dieY = h / 2 / opts.len,
baseRad = Math.PI * 2 / 6;
ctx.fillStyle = 'black';
ctx.fillRect(0, 0, w, h);
function loop() {
	window.requestAnimationFrame(loop); ++tick;
	ctx.globalCompositeOperation = 'source-over';
	ctx.shadowBlur = 0;
	ctx.fillStyle = 'rgba(0,0,0,alp)'.replace('alp', opts.repaintAlpha);
	ctx.fillRect(0, 0, w, h);
	ctx.globalCompositeOperation = 'lighter';
	if (lines.length < opts.count && Math.random() < opts.spawnChance) lines.push(new Line);
	lines.map(function(line) {
		line.step()
	})
}
function Line() {
	this.reset()
}
Line.prototype.reset = function() {
	this.x = 0;
	this.y = 0;
	this.addedX = 0;
	this.addedY = 0;
	this.rad = 0;
	this.lightInputMultiplier = opts.baseLightInputMultiplier + opts.addedLightInputMultiplier * Math.random();
	this.color = opts.color.replace('hue', tick * opts.hueChange);
	this.cumulativeTime = 0;
	this.beginPhase()
}
Line.prototype.beginPhase = function() {
	this.x += this.addedX;
	this.y += this.addedY;
	this.time = 0;
	this.targetTime = (opts.baseTime + opts.addedTime * Math.random()) | 0;
	this.rad += baseRad * (Math.random() < .5 ? 1 : -1);
	this.addedX = Math.cos(this.rad);
	this.addedY = Math.sin(this.rad);
	if (Math.random() < opts.dieChance || this.x > dieX || this.x < -dieX || this.y > dieY || this.y < -dieY) this.reset()
}
Line.prototype.step = function() {++this.time; ++this.cumulativeTime;
	if (this.time >= this.targetTime) this.beginPhase();
	var prop = this.time / this.targetTime,
	wave = Math.sin(prop * Math.PI / 2),
	x = this.addedX * wave,
	y = this.addedY * wave;
	ctx.shadowBlur = prop * opts.shadowToTimePropMult;
	ctx.fillStyle = ctx.shadowColor = this.color.replace('light', opts.baseLight + opts.addedLight * Math.sin(this.cumulativeTime * this.lightInputMultiplier));
	ctx.fillRect(opts.cx + (this.x + x) * opts.len, opts.cy + (this.y + y) * opts.len, 2, 2);
	if (Math.random() < opts.sparkChance) ctx.fillRect(opts.cx + (this.x + x) * opts.len + Math.random() * opts.sparkDist * (Math.random() < .5 ? 1 : -1) - opts.sparkSize / 2, opts.cy + (this.y + y) * opts.len + Math.random() * opts.sparkDist * (Math.random() < .5 ? 1 : -1) - opts.sparkSize / 2, opts.sparkSize, opts.sparkSize)
}
loop();
window.addEventListener('resize',
function() {
	w = c.width = window.innerWidth;
	h = c.height = window.innerHeight;
	ctx.fillStyle = 'black';
	ctx.fillRect(0, 0, w, h);
	opts.cx = w / 2;
	opts.cy = h / 2;
	dieX = w / 2 / opts.len;
	dieY = h / 2 / opts.len
});
</script>
</body>
</html>